Pamrevlumab

SAN FRANCISCO, April 24, 2024 (GLOBE NEWSWIRE) -- FibroGen, Inc. (NASDAQ: FGEN) today announced that clinical data from the dose escalation portion of the Phase 1b/2 study of FG-3246 in combination with enzalutamide in patients with metastatic castration resistant prostate cancer have been selected for a poster presentation at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting taking place May 31-June 4, 2024 in Chicago, Illinois. Details for the poster presentation are as follows: Session: Poster Session – Genitourinary Cancer – Prostate, Testicular, and Penile Title: A Phase 1b dose escalation study of FOR46, a novel antibody-drug conjugate targeting a tumor-specific epitope of CD46, in combination with enzalutamide (Enza) in patients with metastatic castration resistant prostate cancer (mCRPC). Presenter: Nonna Shakhnazaryan and Dr. Rahul Aggarwal, MD from the UCSF Helen Diller Family Comprehensive Cancer Center Abstract number: 5066 Poster number: 472 Date and Time: June 2, 2024 at 9:00-12:00 AM CDT About FG-3246 FG-3246 (also known as FOR46) is a potential first-in-class fully human antibody-drug conjugate (ADC), exclusively in-licensed from Fortis Therapeutics, and is being developed by FibroGen for metastatic castration-resistant prostate cancer and other tumor types. FG-3246 binds to a tumor-specific epitope of CD46, a cell receptor target, that induces internalization upon antibody binding, is present at high levels in prostate cancer and other tumor types, and demonstrates limited expression in most normal tissues. FG-3246 is comprised of an anti-CD46 antibody, YS5, linked to the anti-mitotic agent, MMAE, which is a clinically and commercially validated ADC payload. FG-3246 has demonstrated anti-tumor activity in both preclinical and clinical studies. FG-3246 is currently in an ongoing investigator-initiated Phase 1b/2 study being conducted at UCSF to evaluate it in combination with enzalutamide with initial data expected in mid-2024, and a biomarker trial using a PET biomarker for CD46 using the same antibody backbone. We anticipate the initiation of a Phase 2 monotherapy dose optimization study of FG-3246 in metastatic castration-resistant prostate cancer in 2H 2024. FG-3246 is an investigational drug and not approved for marketing by any regulatory authority. About FibroGen FibroGen, Inc. is a biopharmaceutical company focused on accelerating the development of novel therapies at the frontiers of cancer biology. Pamrevlumab, a fully human anti-CTGF monoclonal antibody, is in clinical development for the treatment of metastatic pancreatic cancer and locally advanced unresectable pancreatic cancer (LAPC). Roxadustat (爱瑞卓®, EVRENZOTM) is currently approved in China, Europe, Japan, and numerous other countries for the treatment of anemia in chronic kidney disease (CKD) patients on dialysis and not on dialysis. Roxadustat is in clinical development for chemotherapy-induced anemia (CIA) and a Supplemental New Drug Application (sNDA) has been accepted for review by the China Health Authority. FG-3246 (also known as FOR46), a first-in-class antibody-drug conjugate (ADC) targeting CD46 is in development for the treatment of metastatic castration-resistant prostate cancer. This program also includes the development of an associated CD46-targeted PET biomarker. In addition, FibroGen has expanded its research and development portfolio to include two immuno-oncology product candidates for the treatment of solid tumors. For more information, please visit FibroGen, Inc. Investors: David DeLucia, CFA Vice President of Corporate FP&A / Investor Relations ir@fibrogen.com Media: Meichiel Keenan Director, Investor Relations and Corporate Communications media@fibrogen.com

Phase 1 results for anti-CD46 antibody drug conjugate FG-3246 follow a run of four late-stage flops for Fibrogen last year. FibroGen had a run of bad luck in its phase 3 trials last year, but phase 1 data posted this week suggest its earlier-stage pipeline still has potential. A phase 1 study of the anti-CD46 antibody drug conjugate (ADC) FG-3246 in 56 patients with metastatic castration-resistant prostate cancer demonstrated median progression-free survival (PFS) of 8.7 months and a prostate-specific antigen (PSA) decrease of 50% or more in 36% of participants. William Blair analysts branded the results “encouraging” and said they “appear to offer numerically improved efficacy metrics relative to alternate novel hormone therapy.” They also noted that Novartis’ radioligand therapy Pluvicto scored a PSA50 response of 58% and a PFS of 12 months in a phase 3 trial among a similar patient population, while a combination of Exelixis’ Cabometyx and Roche’s Tecentriq demonstrated PFS of 4.2 months in a separate phase 3 prostate cancer trial. “While we acknowledge that the FDA cautions drawing solid conclusions based on the point estimate of progression-free survival from single-arm studies (i.e. it should preferably be interpreted in the context of hazard ratios), we believe the heavily pretreated nature of the study population, coupled with enrolling an unselected population, warrants further investigation of FG-3246 in prostate cancer,” the analysts concluded in an April 4 note. In FibroGen’s postmarket release yesterday, Chief Medical Officer Deyaa Adib, M.D., pointed out that the 8.7 month PFS rate related to “heavily pre-treated patients who received biologically active doses of FG-3246 in the second line or later setting prior to chemotherapy.” “These phase 1 data provide evidence of a favorable safety profile and promising clinical activity as further evidenced by prostate-specific antigen reduction of ≥ 50% and shrinking of measurable disease,” Adib added. “We look forward to publishing the totality of the phase 1 data as we advance the program further in the clinic.” San Francisco-based FibroGen licensed FG-3246 from Fortis Therapeutics back in May 2023 for an $80 million option fee with up to $200 million biobucks attached. The deal helped FibroGen bulk up the back end of a pipeline that had been narrowly focused around approved oral anemia drug Evrenzo and pamrevlumab. A run of four phase 3 duds since then didn’t help improve the outlook for FibroGen’s pipeline. Evrenzo received a big clinical blow—ultimately leading AstraZeneca to end its partnership over the drug—followed by a trio of failures for pamrevlumab in non-ambulatory Duchenne muscular dystrophy and idiopathic pulmonary fibrosis. The biotech will be hoping FG-3246 can break the run of bad luck. The ADC is also being evaluated in a phase 1/2 study for metastatic castration-resistant prostate cancer in combination with Pfizer and Astellas' Xtandi with an initial readout expected in mid-2024. FibroGen is planning to kick off a separate phase 2 trial for FG-3246 as a monotherapy in the second half of this year.